Prophecies and Those Who Hear Them

[fanofminerva]

No: HPFGUIDX 132464

I have a question about prophecies in the Potterverse.  What if no one 
is around to hear when a prophecy is made?  In POA, Trelawney seemed 
to have no recollection that she had given a prophecy.  If Harry had 
not gone back, he would not have heard it.  What, then, would have 
happened to the prophecy?  If it is "orbed" then who "orbs" it?  Would 
this person(s) not have some magical access to all prophecies?  

I know these are all speculative questions, but given the prominence 
of the prophecy about LV and (?)Harry Potter, it seems that 
understanding prophecies in the Potterverse would be quite helpful.

Julie